1. Field of the Invention
The present invention relates generally to a technique for incorporating an RF transceiver onto the body of an electronic device. More particularly, it relates to a fully integrated, device-independent RF transmit/receive module that combines the antenna and associated electronics into a single package and can be installed and used on a variety of electronic devices for the purpose of communicating with other electronic devices.
2. Background of the Invention
As portable devices become more capable of storing and displaying information, a need inherently arises for data transfers between these devices. One example of this type of transfer includes the downloading of personal schedules and contact information from a computer to a personal digital (or data) assistant (PDA). This communication link is typically established via cumbersome cabling and often proprietary connectors. Wireless communication networks allow this type of data transfer to take place without the need for physical connections.
Generally stated, wireless communication allows for the transmission and reception of data without the need for physical connections. This data can take many forms including audio and video signals or even facsimile and text messages. The progress of wireless telephony and wireless communication between people has been aided by the development of cellular standards such as GSM in Europe and AMPS, CDMA, and TDMA in North America. With the development of standards such as Bluetooth and IEEE 802.11, wireless communication between electronic devices is becoming even more prevalent.
The Bluetooth and IEEE 802.11 wireless communication standards allow for short range radio links between electronic devices. In general, these standards allow for point-to-point or point-to-multipoint wireless communications. The Bluetooth standard is generally used in wireless personal area networks (WPAN) and allows users to transfer information between mobile PCs, mobile phones and other devices. The IEEE 802.11 standard is generally used for wireless local area networks (WLAN) and may be used to communicate between PCs, PDAs, and other computing devices. Both offer the advantage of allowing a user or users to establish communications between two or more electronic devices for a data transfer without the need for cumbersome cabling and connectors. Radios which operate according to these standards may transmit or receive signals in the unlicensed, universal ISM (Industrial, Scientific, and Medical) radio frequency band between 2.4 and 2.4835 GHz.
The IEEE 802.11 standard and the IrDA standards also allow for wireless communication via infrared (IR) transmission in the 300 to 428,000 GHz range. IR communication may offer greater security than RF communication, but also requires a direct “line of sight” link between the communicating devices and can be adversely affected by environmental influences. RF transmission, on the other hand, allows for communication around comers and through walls or barriers. Security and interference problems associated with RF communications are alleviated with the implementation of direct sequence or frequency hopping spread spectrum techniques. Other measures such as error correction and collision avoidance help ensure robust data transfers.
Current wireless point to point communication solutions exist in either a device model-dependent proprietary solution designed into the main body of a product or may take the form of a PCMCIA card for use with notebook computers. PCMCIA (Personal Computer Memory Card International Association) is an international standards body and trade association that was founded to establish standards for Integrated Circuit cards and to promote interchangeability among mobile computers. PCMCIA cards (also referred to as PC Cards) and slots provide a means of adding external peripheral components such as a modem or a Network Interface Card to a notebook computer. Companies such as Motorola and Samsung are currently offering PC Card solutions for Bluetooth WPANs and/or IEEE 802.11 WLANs.
Other point to point wireless communication solutions may take the form of Mini PCI cards that are integrated inside a notebook computer. Mini PCI cards are miniature form factor versions of the PCI (Peripheral Component Interconnect) expansion cards used in desktop computers. PCI and Mini PCI cards plug into a high-speed input/output PCI bus used for connecting performance-critical peripherals to the memory, chipset, and processor. For example, video cards, disk storage devices, and high-speed network interfaces generally use a bus of this sort.
Wireless communication devices that take the form of Mini PCI or PC cards are convenient in that they are based on existing computer hardware and bus architecture. Unfortunately, these solutions also occupy existing expansion slots that could otherwise be used for peripherals such as network cards and video drivers. Furthermore, any solution that places the RF antenna in close proximity to a computer's motherboard and microprocessor is less than ideal. The computer processor and chipset generate noise which results in signal degradation and attenuation. Attenuation is also a result of RF signal multipathing that results from placing the RF antenna in a position where signals can be obstructed by the notebook computer screen and other parts of the system such as magnesium cases or EMI-shielded plastic components.
Experiments show that for significant improvements in performance, the RF antenna in a wireless communication device should be placed high up in an unobstructed location. To account for this, other conventional wireless point to point communication solutions employ a whip or blade type antenna that is mounted high on the device itself or located external to the device. In devices where the antenna is mounted directly to the communicating device, the antenna usually extends beyond the envelope of the product in which they are installed and may be prone to damage resulting in expensive replacement costs. Examples of these types of antennas are described in U.S. Pat. Nos. 5,644,320 and 5,903,548.
Furthermore, in some conventional designs the radio circuitry is often located separate from the antenna. In cases like this, the antenna must be connected via a coaxial cable or shielded wire assembly to the main radio circuitry, which adds to the cost and introduces signal loss and degradation. In addition to being unsightly, the cable assembly can be a nuisance and become tangled with other wiring or other equipment or suffer damage if routed through moving components such as notebook lid hinges. Furthermore, as product configurations change and locations of the radio components change, each new radio configuration must be re-qualified for use by the FCC.
Another disadvantage of certain existing designs is that as wireless specifications change, radio circuitry may become obsolete. If the radio circuitry and/or the antenna subsystem is hardwired into the parent device, then significant disassembly, component replacement, and downtime are required to bring the communication device up to date.
It is desirable, therefore, to provide a small, low cost, fully integrated radio module that can be assembled as a complete unit that is standardized across product lines. This radio module would preferably be fully contained (i.e., include antenna and all related circuitry) so that no cable or connector losses occur and would be easily installed in a parent device such as a portable computer or a PDA. Furthermore, the configuration of the module would allow for optimal placement with regards to RF signal reception and transmission.